Thermostatic switch assembly



THERMOSTATI C SWITCH AS SEMBLY Filed March 18, 1929 352! Z 40 1a r1 57 11 18 39 INVENTORS [Van/1 A Z0372 Jaw rgnce Z. 775/7714? BY W ATTORNEY-5' Patented July 4, 1933 UNITED STATES PATENT .oFFicE FRANK KUHN Am) LAURENCE H. THOMAS, or nn'rnorr, ivircnrenn, nssienons TO,

AMERICAN ELECTRICAL HEATER COMPANY, OF DETROIT, MICHIGAN, A CORPORA- TION OF MICHIGAN THERMOSTATIC' SWITCH ASSEMBLY Application filed March 18, 1929. Serial No. 848,062/

This invention relates to thermostats and more particularly to a thermostatic switch ASSGIIlblY adapted to make or break an electric c1rcu1t at a certain predetermined temperature.

The invention, while capable of many and liversified uses, finds particular utility in connection with automatic electricirons.

One of the primary objects of the invention is to provide a thermostatic switch having adjustable means associated therewith for varying the temperature at which the switch operates and also having means for limiting the extent of adjustment of the means aforesaid,

-Another object of the invention is to provide an adjustable thermostatic switch of the above type wherein the thermostatic elements, terminal contact members for the elements, and the adjusting mechanism aforesaid for the switch, form a unitary construction which may be readily applied to or detached from the iron as a unit.

A further object of the invention resides in the provision of an adjustable mounting m the thermostatic switch for the adjustable neans whereby the latter may be adjusted relative to the means aforesaid for limiting the extent of adjustment to insure breaking he circuit when the proper temperature is reached.

Other objects and novel features of construction of this invention will be made more apparent as this description proceeds, especially when considered in connection with the accompanying drawing, wherein Figure 1 is a top plan view of a thermostatic switch constructed in accordance with our invention,

Figure 2 is a longitudinal sectional view through the construction shown in Figure 1,

Figure 3 is a cross section taken on the plane indicated by the line 3-3 on Figure 2, and

Figure 41- is a fragmentary side elevational View partly insection showing a slightly modified form of construction.

Referring now to the embodiment of the invention as illustrated in the drawing, the numeral 10 represents a casing having a base 11, and the numerals 12 and 13 designate bimetallic thermostatic strips laterally spaced from each other at one end by the spacer 14 having direct contact with the thermostatic strip 12. Each bi-metallic strip extends outwardly from its point of support and the free ends thereof are provided with suitable contacts 15 and 16 respectively, adapted to cooperate for completing an electric circuit. The strips 12 and 13 are otherwise insulated from each other, for example,by the mica sheet 17 interposed between the element 13 and thespacer 1 1. In this connection it will be noted that the strip 12 is likewise insulated from metallic contact with the base 11 by nieansof a'mica strip 18 extendingfor substantially the full length of the base. The thermostatic elements 12 and 13 are so constructed and arranged that under increasing temperature conditions both elements are deflected laterally in the same direction and in the construction shown both of the elements move away from the basell upon increase in temperature. r a

The thermostatic elements are adapted to be connected into a suitable electric circuit by terminals 19 and 20 respectively extending laterally of the respective elements. As shown in Figure 2 of the drawing the terminal 20 is formed on the spacer 14 bearing against the element 12,. while the terminal 20 is formed integral with a second spacer 21 contacting with the element 13. It-will further be noted from Figure 3 of the drawing that the thermostatic elements, spacers and insulating sheets 17 and 18 are secured to the base 11 as a unit by a single fastening element 24 extending through the aforesaid members and riveted to a clamping member 25 seated upon the spacer 21 and insulated therefrom.

For breaking the circuit a stop is provided in the path of the thermostatic element 12, spaced in such a manner as to engage the outer end thereof when the deflection of the stop 26 and for preventing the contactpoint 31 from engaging the strip l2 when the latter is in the position shown in Figure 2 a fixed stop 32 is provided. The fixed stop comprises a strip 33 projecting upwardly from and formed integral with thefl-ange 29 and adapted to extend in close proximity to the stop 26 so as to engage a projection 34 formed on and extending laterally from the stop 26.

In order to reinforce the portion of the strip 12 adapted to be engaged by the stop the former is provided adjacent the free end thereof with upwardly extending flanges 35.

In theconstruction as described, the circuit is normally closed when the thermostatic elements are at room temperature by reason of the contacts 15 and 16 being in engagement. A certain pressure is maintained between the contacts by virtue of the resiliency of the thermostatic elements themselves. Upon a rise in temperature both the thermostatic el-ements move laterally away from the base 11 of the casing until the element 12 strikes the stop 26 whereupon movement of the element'l2 is retarded so that a further increase in temperature causes the element 13 to move away from the element 12 and separate the contacts 15 and 16. By adjusting the stop 26 the thermostat may be set to break the circuit at a plurality of predetermined temperatures.

The modification illustrated in Figure 4 differs from-the first described form of the invention in that the adjustable element 36 for the switch is threadedly mounted in a nut 37 having a shankportion 38 extending through a suitable opening formed in a flange 39 extending laterally from the'thermostatic switch casing. For securing the nut to the flange 39, the lower end portions of the shank 38 are bent over upon the under surface of the flange in substantially the same manner as r the sleeve 28 in the first described form of the invention. The nut 37 in the present instance, however, is capable of rotation relative to theflange 39 and to the element 36 and is normally held from such rotation by a spring lock washer 40. As shown in Figure 4 the washer iO surrounds the shank portion 38 intermediate the body portion of the nut and the flange'39.

With the foregoing construction it will be noted that the element 36, in addition'to being rotatably adjustable as in the first described form of the invention, is also capable of axial adjustment independent of the fixed stop. An arrangement of this character renders possible accurately varying the position of the adjustable element relativeto the fixed stop prior to assembling the switch upon the heater so that when the temperature of the heater reaches a certain predetermined amount the adjustable stop will immediately break the circuit. Thus any inaccuracies in the manufacture of the thermostat may be compensated for and the separation of the thermostatic switch contacts when the maximum temperature-is reached is insured.

What we claim as our invention is:

l. A thermostatic switch comprising a casing, thermostatic elements supported upon one wall of the casing and adapted to move laterally under temperature changes, cooperating contacts on therespectiv-e elements, an adjustable stop threadedly mounted upon the casing and having a portion arranged in the path of one of the thermostatic elements for intercepting the same at predetermined points in the deflection thereof to permit separation of said contacts under changing temperature conditions, said adjustable stop having another portion provided with a projection, and a fixed stop projecting upwardly from the casing in the path of travel of the projection for limiting the extent of adjustment of said first mentioned stop.

2. A thermostatic switch comprising a casing having a base and an end wall extending upwardly from the base and terminating in a lateral flange arranged sub stantial'ly parallel with the base, thermo static elements supported upon the base and adapted to move away from the base under temperature changes, cooperating contacts on the respective elements, means for interceptingone of'said elements at different predetermined points in the deflection thereof to permit separation of said contacts under changing temperature conditions, said means including an adjustable stop threadedly mounted upon the lateral flange aforesaid,

and means for limiting the extent of adjustment of said stop including a member extending upwardly from the flange and adapted to engage a projection upon the stop. 7

3. In a thermostatic switch assembly, the combination of a casing having a base and an end wall terminating in a flange arranged parallel with the base, thermostatic elements carried by the base and movable away from the latter under temperature changes, cooperating contacts on the respective elements, an adjustable stop threadedly mounted in the flange aforesaid and having one end arranged in the path of travel of one of said elements for intercepting the same to permit separation of said contacts under changing temperature conditions, and a fixed stop extending upwardly from and formed integral with the said flange and engageable with the adjustable stop for limiting the adjustment of the first mentioned'stop.

4-. A thermostatic switch comprising thermostatic elements adapted to move laterally under temperature changes, cooperating contacts on the respective elements, a rotatable rod having a portionof the lower end thereof arranged in the path of travel-of one of said elements for intercepting the same at a predetermined point to permit separation of said contacts, and means for axially adj usting said rod while holding the same from rotation.

5. A thermostatic switch comprising thermostatic elements adapted to move laterally under temperature changes, cooperating contacts on the respective elements, a rotatable adjustable stop for intercepting one of said elements at different predetermined point-s in the deflection thereof to permit separation of said contacts under changing temperature conditions, and a rotatable member carried by the switch and constituting a mounting for said stop capable of axially adjusting the latter without rotating the same.

6. A thermostatic switch comprising a casing and thermostatic elements carried by the casing and adapted to move laterally under temperature changes, cooperating con tacts on the respective elements, a rotatable adjustable stop for intercepting one of the elements at different predetermined points in the deflection thereof to permit separation of said contacts under changing temperature conditions, a rotatable mounting for said stop carried by the casing and operable upon rotation to axially adjust the stop irrespective of the rotation thereof, and means for resisting rotation of said mounting.

7. A thermostatic switch comprising thermostatic elements adapted to move laterally under temperature changes, cooperating contacts on the respective elements, an adjustable stop for intercepting one of said elements at difierent predetermined points in the deflection thereof to permit separation of said contacts under changing temperature conditions, means for limiting the extent of adjustment of said stop, and adjustable means operable independent of said limiting means for adjusting the stop to vary the distance between the latter and first-mentioned thermostatic element.

8. A thermostatic switch comprising thermostatic elements adapted to move laterally under temperature changes, cooperating contacts on the respective elements, a rotatably adjustable stop for intercepting one of the elements at different predetermined points in the deflection thereof to permit separation of said contacts under changing temperature conditions, a fixed member engageable with said stop for limiting the extent of adjustment of the same, and means for initially adjusting said stop independent of the fixed member as and for the purpose set forth.

9. A thermostatic switch comprising, a supporting member, thermostatic elements adapted to move laterally relative to said member under temperature changes, cooperating contacts on the respective elements, a rotatable stop having a portion at one end thereof arranged in the path of travel of one on the respective elements,

of said elements for intercepting the same at l V a predetermined point in the deflection thereof to permit separation of said contacts, a mounting for the stop operable upon rotation of the stop relative thereto to vary the distance between the portion aforesaid of the stop and first-named thermostatic element permitting separation of the contacts under changing temperature conditions, means for limiting the extent of rotative adjustment of the stop relative to the mounting, and a connection between the mounting and supporting member permitting rotation of the mounting relative to the stop and thereby permit varying the distance aforesaid between the stop and said first-named thermostatic element without interference by said limiting means.

10. A thermostatic switch comprising thermostatic elements adapted to move laterally under temperature changes, cooperating c011- tacts on the respective elements, a rotatably adjustable stop having a portion at one end thereof arranged in the path of travel of one of said elements for intercepting the same at different predetermined points in the deflection thereof to permit separation of said contacts under changing temperature conditions, means for limiting the rotative adjustment of the stop, and means for adjusting the position of the stop relative to said first-named thermostatic element without interference with the limiting means aforesaid.

11. A thermostatic switch comprising, a support, thermostatic elements adapted to move laterally relative to the support under temperature changes, cooperating contacts a threaded stop having a portion at one end thereof arranged in the path of travel of one of the thermostatic elements for intercepting the same at a predetermined point in the deflection thereof to permit separation of said contacts, a mounting on the support for threadedly receiving said stop and operable upon rotation of the latter relative thereto to vary the dis tance between the portion aforesaid of the stop and first-named thermostatic element to permit separation of said contacts under changing temperature conditions, means for limiting the extent of rotation of the stop relative to said mounting, and a connection between the mounting and support permitting rotation of the mounting relative to the stop and thereby provide for varying the distance between the stop and first-named thermostatic element without interference by said limiting means.

In testimony whereof we alfix our signatures.

FRANK KUHN. LAURENCE H. THOMAS. 

